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TiNi-based films for elastocaloric microcooling. Fatigue life and device performance

Ossmer, H.; Chluba, C.; Kauffmann-Weiss, S.; Quandt, E.; Kohl, M.



Abstract (englisch): The global trend of miniaturization and concomitant increase of functionality in microelectronics, microoptics, and various other fields in microtechnology leads to an emerging demand for temperature control at small scales. In this realm, elastocaloric cooling is an interesting alternative to thermoelectrics due to the large latent heat and good down-scaling behavior. Here, we investigate the elastocaloric effect due to a stress-induced phase transformation in binary TiNi and quaternary TiNiCuCo films of 20 μm thickness produced by DC magnetron sputtering. The mesoscale mechanical and thermal performance, as well as the fatigue behavior are studied by uniaxial tensile tests combined with infrared thermography and digital image correlation measurements. Binary films exhibit strong features of fatigue, involving a transition from Lüders-like to homogeneous transformation behavior within three superelastic cycles. Quaternary films, in contrast, show stable Lüders-like transformation without any signs of degradation. The elastocaloric temperature change under adiabatic conditions is −15 K and −12 K for TiNi and TiNiCuCo films, respectively. First-of-its-kind heat pump demonstrators are developed that make use of out-of-plane deflection of film bridges. Owing to their large surface-to-volume ratio, the demonstrators reveal rapid heat transfer. The TiNiCuCo-based devices, for instance, generate a temperature difference of 3.5 K within 13 s. The coefficients of performance of the demonstrators are about 3.


Zugehörige Institution(en) am KIT Institut für Mikrostrukturtechnik (IMT)
Institut für Technische Physik (ITEP)
Publikationstyp Zeitschriftenaufsatz
Jahr 2016
Sprache Englisch
Identifikator DOI: 10.1063/1.4948271
ISSN: 2166-532X
URN: urn:nbn:de:swb:90-549744
KITopen ID: 1000054974
HGF-Programm 43.22.01; LK 01
Erschienen in APL Materials
Band 4
Heft 6
Seiten 064102/1-6
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